Generally, a flow path unit used for an ink-jet head of a printer is formed by laminating a plurality of plates having holes. The holes formed at the plurality of plates are laminated and communicate with one another, thereby forming ink flow paths through which ink flows. The ink which flows through the ink flow paths are discharged from nozzle holes formed at a lowermost plate. In this case, if the plurality of plates are not laminated precisely, variations will occur in the volume or flow path resistance of flow paths to be formed, and the ink discharge performance from the nozzle holes will be disrupted.
Thus, in order to align two plates, JP-A-2004-128224 discloses a method for inspecting a positional deviation. The method disclosed in JP-A-2004-128224 includes: holding a plate as a first electronic component on a receiving table; holding a plate as a second electronic component to a bottom surface of a position adjusting mechanism which is located above the first electronic component; and inspecting the positional deviation between the first electronic component and the second electronic component by a camera. The first electronic component has alignment holes passing therethrough in its thickness direction. The receiving table has see-through holes formed at positions corresponding to the alignment holes. Alignment marks smaller than the alignment holes are formed at a position corresponding to the alignment hole on the surface of the second electronic component which faces the first electronic component. Moreover, a dry film resist which serves as an adhesive is formed on the surface of the second electronic component which faces the first electronic component. The dry film resist has see-through holes at positions corresponding to the alignment marks.
As the method of inspecting the positional deviation described in JP-A-2004-128224, it is necessary to arrange the camera under the receiving table to correspond to the alignment holes to hold the alignment holes and the alignment marks within a focal depth, and then the camera picks up an image upward. In this state, the deviation between the center of the alignment hole and the center of the alignment mark is inspected.
However, in the positional deviation inspection method described in JP-A-2004-128224, as the number of plates laminated increases, the distance between the lowermost plate of the receiving table and the plate held by the position adjusting mechanism which is laminated above the lowermost plate may increase. Therefore, it is difficult to hold all the plates within the focal depth. Then, whenever a positional deviation is inspected, the camera should be focused on the lowermost plate or focused on the plate held by the position adjusting mechanism, and therefore, inspection efficiency degrades.